HISTIDINE-DECARBOXYLASE PRODUCTION BY LACTOBACILLUS-HILGARDII - EFFECT OF ORGANIC-ACIDS

Histidine decarboxylase production from Lactobacillus hilgardii 5w, is olated from wine, was inhibited by the presence of L-malic acid in the basal culture medium. The inhibition was related to L-malic acid conc entration. The maximal production of the enzyme at 12 h of culture inc ubated at 30 degrees C was inhibited 71% by 2 g/L L-malic acid and 47% by 0.5 g/L. In these conditions L-malic acid consumption was 16% and 20% respectively. The addition of 300 mg/L citric acid to the basal me dium stimulated the enzyme production from 9 to 45 nmoles/min/mg dry w eight, and the increase was correlated with citric acid concentration. When different concentrations of L-malic acid were added to the basal medium plus 200 mg/L citric acid, reversion of stimulation was observ ed, achieving the maximum at a concentration of 2 g/L. In this case, c itric acid comsumption was not modified, whereas L-malic acid utilizat ion was higher.